Does the remorse and distress over past shortcomings and mistakes constitute a punishment from God?

If chest tightness is due to remorse over neglecting acts of obedience or falling into prohibited acts, then it is a sign of good and an impetus for repentance and rectitude. A believer always blames and admonishes himself. It cannot be definitively stated that this is a punishment, but sins have many harms, including alienation in the heart and chest tightness. Therefore, one should frequently read texts that encourage repentance and performing acts of obedience, and that give glad tidings to those who repent of the acceptance of their repentance, so that activity for acts of obedience increases and éloignement from sins occurs, and the chest expands. So, do not despair of Allah's mercy.